Beacon interval with boundary time points (btps) to improve latency for time sensitive traffic (tst) in extremely high throughout (eht) wlans

ABSTRACT

Embodiments of a beacon interval with boundary time points (BTPs) to improve latency for time sensitive traffic (TST) in Extremely High Throughout (EHT) WLANS are disclosed herein. In some embodiments, a non-access point (AP) station (STA) is configured to decode a beacon frame received from an AP STA. The beacon frame may indicate one or more BTPs within a beacon interval (BI). The non-AP STA may obtain a transmission opportunity (TXOP) for a transmission to the AP STA. The TXOP may be bounded by the one or more BTPs. The non-AP STA may encode a PPDU for transmission to the AP STA during the TXOP.

PRIORITY CLAIM

This application claims the benefit of priority under 35 USC 119(e) toU.S. Provisional Patent Application Ser. No. 62/927,284, filed Oct. 29,2019 [reference number AC5847-Z] which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

Embodiments pertain to wireless communications. Some embodiments relateto wireless local area networks (WLANs). Some embodiments relate to WLANcommunications in accordance with the IEEE 802.11be draft standard(i.e., Extremely High Throughput (EHT)). Some embodiments relate tolatency improvement in WLANs.

BACKGROUND

One issue with communicating data over a WLAN is latency. End to enddelay is an important key performance indicator in wireless networks.Broad expansion of WLANs and their technological evolution creates newuse cases involving transfer of time sensitive traffic such asvoice-over-internet protocol (VoIP), video streaming, videoconferencing, gaming, etc. In such applications, time sensitive traffic(TST) may require low latency to satisfy user requirements and/or toprovide good experience. TST is usually characterized by a predictabletraffic pattern such as a fixed interarrival time, and load and packetsize. The major contributing factors to high delays are network load(e.g., the more traffic is on air, the less time is for TST to bedelivered), contention/collisions (e.g., the more devices is in network,the harder for TST to access the medium), and transmission/duration(e.g., each device in a wireless network can occupy medium for a longtime leaving STA with TST no chances to access the medium). Thesefactors may lead to a high, unpredictable end-to-end latency in awireless network. Thus, there are general needs for latency reduction inWLANs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a beacon interval including a beacon frame andboundary time points (BTPs) in accordance with some embodiments.

FIG. 2 is a functional block diagram of a wireless communication station(STA) in accordance with some embodiments.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

A conventional approach to provide required latency is to use variousmechanisms, such as prioritization, better control from the access point(AP) side and complicated scheduling. For example, TST traffic mayutilize higher access category like AC_VO to contend for the mediumwhile other devices use lower access category like AC_BE. The IEEE802.11ax standard allows an AP to control channel access using atrigger-based mechanism and multi-user (MU) enhanced distributed channelaccess (EDCA) parameters set to control channel access within wirelessnetwork. An AP may utilize target-wake up time (TWT) schedulingmechanism to control devices transmission opportunities.

While a station (STA) with TST may utilize a higher access category toaccess the channel, it does not guarantee that this STA always getaccess. Even more, another device may capture the medium for a long-timepreventing STA channel access. An AP may use a trigger frame (TF) totrigger a STA for uplink transmission. In order to do that, the AP maystill need to perform contention to access the medium subject toproblems above. While TWT is an option, it requires complicatedscheduling at AP side and has coexistence issues with the OBSS which maynot honor provided TWT schedule

Embodiments disclosed herein increase number of contention opportunitiesfor STAs with TST and to provide such devices with more chances toaccess the medium. These embodiments allow STAs with TST to haveimproved peak latency which therefore improves the user experience.

Embodiments disclosed herein use Boundary Time Points (BTPs) to addressthe issues discussed above. In these embodiments, a BTP is a specialtime point(s) within a beacon interval and may be distributed by an APin a Beacon frame. AP/STAs may use a BTP as an additionalrestriction/parameter when organizing TX operation/starting TXOP. Insome embodiments, any TXOP or transmission will not extend beyond BTP.Such a restriction may force to stop all devices from a TX/RX operationbefore a BTP giving more chances for a TST STA to obtain TXOP at adesired time. In these embodiments, devices in the network shallstart/resume their backoff after BTP following regular EDCA channelaccess rules.

Some embodiments provide for an extension for TWT. In these embodiments,enabling BTP at the start of TWT service period (SP) may help preventother devices in a network from transmitting over the SP. This willincrease chances of a device with a negotiated TWT SP to receive dataimmediately. A TWT STA in Power Save (PS) mode outside of TWT SP willspend less energy in active state to receive pending data.

Some embodiments provide for an extension for Multi-link. In theseembodiments, EHT devices with multi-link capabilities may benefit fromusing BTP in a following way: An EHT AP can synchronize BTP allocationin multiple links to increase chances for synchronized multi-linkoperation. In such case, an EHT AP or an EHT STA will initiatecontention at the same time on multiple links, which increase chances ofobtaining medium on more than one at a time and to perform simultaneoussynchronized transmission.

FIG. 1 illustrates a beacon interval 106 including a beacon frame 102and boundary time points (BTPs) 104 in accordance with some embodiments.Embodiments disclosed herein are directed to a beacon interval 106 withboundary time points (BTPs) 104 to improve latency for time sensitivetraffic (TST) in Extremely High Throughout (EHT) WLANS.

In some embodiments, a non-access point (AP) station (STA) is configuredto decode a beacon frame 102 received from an AP STA. The beacon frame102 may indicate one or more boundary time points (BTPs) 104 within abeacon interval (BI) 106. The non-AP STA may obtain a transmissionopportunity (TXOP) 108 for a transmission to the AP STA. The TXOP 108may be bounded by the one or more BTPs 104. In these embodiments, thenon-AP STA may encode a PPDU for transmission to the AP STA during theTXOP 108.

In accordance with embodiments disclosed herein, the use of BTPs 104within a beacon interval 106 provide more opportunities to access themedium for STAs by restricting STAs from having TXOP 108 transmissionsthat extend beyond a BTP 104. This is particularly beneficial for STAsthat have tight traffic end-to-end delay constraints. In theseembodiments, if the medium is clear at a BTP, a STA (either a non-AP STAor an AP STA) with time sensitive traffic will have more chances ofaccessing the medium, particularly if the STA uses a higher accesscategory to access the medium. In some embodiments, an AP STA on theother hand may not necessarily be constrained by the BTPs 104. Theseembodiments are discussed in more detail below.

In some embodiments, the non-AP STA may either start or resume anybackoff for channel access after any one or more of the BTPs 104 inaccordance with an enhanced distributed channel access (EDCA) channelaccess procedure. In some embodiments, the non-AP STA may either startor resume any backoff after any one or more of the BTPs 104 for channelaccess for time-sensitive traffic (TST) using a higher access categoryto access the medium (e.g., TST may use higher priority accesscategories such video and voice traffic). Accordingly, the use of BTPs104 will allow a STA with TST to have more opportunities to access themedium since other STAs will be prohibited from acquiring the medium forlong periods of time that extend beyond a BTP 104.

In some embodiments, a least some of the BTPs 104 may be aligned withtarget-wake up time (TWT) service periods (SPs) and indicated in abroadcast TWT element (or field) of the beacon frame. Embodimentsdisclosed herein will help prevent another station from acquiring a TXOP108 that extends beyond a BTP allowing an AP STA to deliver thescheduled traffic to the STA within the negotiated TWT SP. Without theuse of BTPs 104, even if an AP and a STA negotiated a TWT SP, there isno guarantee that another STA may initiate a TXOP 108 just before theannounced TWT SP. The initiated TXOP 108 may be long enough to cover thestart and/or a substantial part of TWT SP leaving little or no room forthe AP to deliver the scheduled traffic to the STA within the negotiatedSP.

In some embodiments, when the AP STA is an EHT AP with multi-linkcapability, and when the non-AP STA is an EHT STA with multi-linkcapability, the non-AP STA is configured to decode beacon framesreceived on multiple links. The beacon frames may indicate one or moreBTPs 104. In these embodiments, when the BTPs 104 are synchronized bythe AP STA on the multiple links, the non-AP STA is configured tosynchronize contention for EDCA channel access on the multiple links. Inthese embodiments, a non-AP STA may initiate or resume contention forEDCA channel access at the same time on the multiple links (e.g.,immediately following the BTP on the links).

In some embodiments, the beacon frame 102 may include a BTP field toindicate the locations of the one or more BTPs 104. In theseembodiments, the BTP field may include an offset from a start of thebeacon interval 106 to indicate a first of the BTPs 104. The field mayalso include a periodicity flag when the BTP is periodic. In theseembodiments, a single BTP field may announce multiple period BTPs 104with the beacon interval.

In some embodiments, the one or more BTPs 104 may be signaled as part ofa broadcast target wake-up time (TWT) field using a reserved bitindicating a start of a service period (SP) that is associated with oneof the BTPs 104. In some embodiments, the TXOP 108 is to either endprior to any one of the one or more BTPs 104 or is to start after anyone or the one or more BTPs 104. In some embodiments, the AP STA andnon-AP STA may be part of a BSS and any TXOPs within a BSS channel maybe bounded by the one or more BTPs 104.

Some embodiments are directed to an access point (AP) station (STA). Inthese embodiments, the AP STA may encode a beacon frame 102 fortransmission within a beacon interval (BI) 106. The beacon frame 102 mayindicate one or more boundary time points (BTPs) 104. Non-AP STAsassociated with the AP STA are to be restricted from obtaining atransmission opportunity (TXOP) extending beyond any of the BTPs 104. Inthese embodiments, the AP STA may obtain a transmission opportunity(TXOP) 108 for a transmission to a non-AP STA and encode a PPDU fortransmission to the non-AP STA during the TXOP.

In some embodiments, the TXOP 108 acquired by the AP STA is not boundedby the one or more BTPs 104. In some embodiments, an AP STA is notnecessarily be constrained by the BTPs 104. For example, if an APobtained a TXOP 108 before a BTP, it may use existing mechanisms such aTrigger frame or a reverse-direction grant (RDG) to solicit data fromSTAs as the AP is aware of expected time sensitive traffic around anannounced BTP point.

In some embodiments, when TXOP 108 acquisition by the AP STA is boundedby the one or more BTPs 104, the AP STA may either start or resume anybackoff for channel access after any one or more of the BTPs 104 inaccordance with an enhanced distributed channel access (EDCA) channelaccess procedure.

FIG. 2 is a functional block diagram of a wireless communication station(STA) in accordance with some embodiments. In some embodiments, FIG. 2illustrates a functional block diagram of a communication station thatmay be suitable for use as an AP STA or non-AP STA. The communicationstation 200 may also be suitable for use as a handheld device, a mobiledevice, a cellular telephone, a smartphone, a tablet, a netbook, awireless terminal, a laptop computer, a wearable computer device, afemtocell, a high data rate (HDR) subscriber station, an access point,an access terminal, or other personal communication system (PCS) device.

The communication station 200 may include communications circuitry 202and a transceiver 210 for transmitting and receiving signals to and fromother communication stations using one or more antennas 201. Thecommunications circuitry 202 may include circuitry that can operate thephysical layer (PHY) communications and/or medium access control (MAC)communications for controlling access to the wireless medium, and/or anyother communications layers for transmitting and receiving signals. Thecommunication station 200 may also include processing circuitry 206 andmemory 208 arranged to perform the operations described herein. In someembodiments, the communications circuitry 202 and the processingcircuitry 206 may be configured to perform operations detailed in theabove figures, diagrams, and flows.

In accordance with some embodiments, the communications circuitry 202may be arranged to contend for a wireless medium and configure frames orpackets for communicating over the wireless medium. The communicationscircuitry 202 may be arranged to transmit and receive signals. Thecommunications circuitry 202 may also include circuitry formodulation/demodulation, upconversion/downconversion, filtering,amplification, etc. In some embodiments, the processing circuitry 206 ofthe communication station 200 may include one or more processors. Inother embodiments, two or more antennas 201 may be coupled to thecommunications circuitry 202 arranged for sending and receiving signals.The memory 208 may store information for configuring the processingcircuitry 206 to perform operations for configuring and transmittingmessage frames and performing the various operations described herein.The memory 208 may include any type of memory, including non-transitorymemory, for storing information in a form readable by a machine (e.g., acomputer). For example, the memory 208 may include a computer-readablestorage device, read-only memory (ROM), random-access memory (RAM),magnetic disk storage media, optical storage media, flash-memory devicesand other storage devices and media.

In some embodiments, the communication station 200 may be part of aportable wireless communication device, such as a personal digitalassistant (PDA), a laptop or portable computer with wirelesscommunication capability, a web tablet, a wireless telephone, asmartphone, a wireless headset, a pager, an instant messaging device, adigital camera, an access point, a television, a medical device (e.g., aheart rate monitor, a blood pressure monitor, etc.), a wearable computerdevice, or another device that may receive and/or transmit informationwirelessly.

In some embodiments, the communication station 200 may include one ormore antennas 201. The antennas 201 may include one or more directionalor omnidirectional antennas, including, for example, dipole antennas,monopole antennas, patch antennas, loop antennas, microstrip antennas,or other types of antennas suitable for transmission of RF signals. Insome embodiments, instead of two or more antennas, a single antenna withmultiple apertures may be used. In these embodiments, each aperture maybe considered a separate antenna. In some multiple-input multiple-output(MIMO) embodiments, the antennas may be effectively separated forspatial diversity and the different channel characteristics that mayresult between each of the antennas and the antennas of a transmittingstation.

In some embodiments, the communication station 200 may include one ormore of a keyboard, a display, a non-volatile memory port, multipleantennas, a graphics processor, an application processor, speakers, andother mobile device elements. The display may be an LCD screen includinga touch screen.

Although the communication station 200 is illustrated as having severalseparate functional elements, two or more of the functional elements maybe combined and may be implemented by combinations ofsoftware-configured elements, such as processing elements includingdigital signal processors (DSPs), and/or other hardware elements. Forexample, some elements may include one or more microprocessors, DSPs,field-programmable gate arrays (FPGAs), application specific integratedcircuits (ASICs), radio-frequency integrated circuits (RFICs) andcombinations of various hardware and logic circuitry for performing atleast the functions described herein. In some embodiments, thefunctional elements of the communication station 200 may refer to one ormore processes operating on one or more processing elements.

In some embodiments, an AP and STA may operate in accordance with one ormore of the IEEE 802.11 standards. The IEEE draft specification IEEEP802.11ax/D4.3, is incorporated herein by reference in its entirety.

The Abstract is provided to comply with 37 C.F.R. Section 1.72(b)requiring an abstract that will allow the reader to ascertain the natureand gist of the technical disclosure. It is submitted with theunderstanding that it will not be used to limit or interpret the scopeor meaning of the claims. The following claims are hereby incorporatedinto the detailed description, with each claim standing on its own as aseparate embodiment.

What is claimed is:
 1. An apparatus of a non-access point (AP) station(STA), the apparatus comprising: processing circuitry; and memory,wherein the processing circuitry is configured to: decode a beacon framereceived from an AP STA, the beacon frame indicating one or moreboundary time points (BTPs) within a beacon interval (BI); obtain atransmission opportunity (TXOP) for a transmission to the AP STA, theTXOP bounded by the one or more BTPs; and encode a PPDU for transmissionto the AP STA during the TXOP.
 2. The apparatus of claim 1, wherein theprocessing circuitry is further configured to either start or resume anybackoff for channel access after any one or more of the BTPs inaccordance with an enhanced distributed channel access (EDCA) channelaccess procedure.
 3. The apparatus of claim 2, wherein the processingcircuitry is configured to either start or resume any backoff after anyone or more of the BTPs for channel access for time-sensitive traffic(TST) using a higher access category to access the medium.
 4. Theapparatus of claim 3, wherein a least some of the BTPs are aligned withtarget-wake up time (TWT) service periods (SPs) and indicated in abroadcast TWT element (or field) of the beacon frame.
 5. The apparatusof claim 2, wherein when the AP STA is an EHT AP with multi-linkcapability, and when the non-AP STA is an EHT STA with multi-linkcapability, the processing circuitry is configured to decode beaconframes received on multiple links, the beacon frames indicating one ormore BTPs, wherein when the BTPs are synchronized by the AP STA on themultiple links, the processing circuitry is configured to synchronizecontention for EDCA channel access on the multiple links.
 6. Theapparatus of claim 2, wherein the beacon frame includes a BTP field toindicate locations of the one or more BTPs, the BTP field including anoffset from a start of the beacon interval to indicate a first of theBTPs, wherein the field further includes a periodicity flag when the BTPis periodic.
 7. The apparatus of claim 2, wherein the one or more BTPsare signaled as part of a broadcast target wake-up time (TWT) fieldusing a reserved bit indicating a start of a service period (SP) that isassociated with one of the BTPs.
 8. The apparatus of claim 2, whereinthe TXOP is to either end prior to any one of the one or more BTPs orstart after any one or the one or more BTPs.
 9. The apparatus of claim2, wherein the AP STA and non-AP STA are part of a BSS, and wherein anyTXOPs within a BSS channel are bounded by the one or more BTPs.
 10. Theapparatus of claim 1, wherein the processing circuitry comprises abaseband processor.
 11. A non-transitory computer-readable storagemedium that stores instructions for execution by processing circuitry ofa non-access point (AP) station (STA), wherein the processing circuitryis configured by the instructions to: decode a beacon frame receivedfrom an AP STA, the beacon frame indicating one or more boundary timepoints (BTPs) within a beacon interval (BI); obtain a transmissionopportunity (TXOP) for a transmission to the AP STA, the TXOP bounded bythe one or more BTPs; and encode a PPDU for transmission to the AP STAduring the TXOP.
 12. The non-transitory computer-readable storage mediumof claim 11, wherein the processing circuitry is further configured toeither start or resume any backoff for channel access after any one ormore of the BTPs in accordance with an enhanced distributed channelaccess (EDCA) channel access procedure.
 13. The non-transitorycomputer-readable storage medium of claim 12, wherein the processingcircuitry is configured to either start or resume any backoff after anyone or more of the BTPs for channel access for time-sensitive traffic(TST) using a higher access category to access the medium.
 14. Thenon-transitory computer-readable storage medium of claim 13, wherein aleast some of the BTPs are aligned with target-wake up time (TWT)service periods (SPs) and indicated in a broadcast TWT element (orfield) of the beacon frame.
 15. The non-transitory computer-readablestorage medium of claim 12, wherein when the AP STA is an EHT AP withmulti-link capability, and when the non-AP STA is an EHT STA withmulti-link capability, the processing circuitry is configured to decodebeacon frames received on multiple links, the beacon frames indicatingone or more BTPs, wherein when the BTPs are synchronized by the AP STAon the multiple links, the processing circuitry is configured tosynchronize contention for EDCA channel access on the multiple links.16. The non-transitory computer-readable storage medium of claim 12,wherein the beacon frame includes a BTP field to indicate locations ofthe one or more BTPs, the BTP field including an offset from a start ofthe beacon interval to indicate a first of the BTPs, wherein the fieldfurther includes a periodicity flag when the BTP is periodic.
 17. Thenon-transitory computer-readable storage medium of claim 12, wherein theone or more BTPs are signaled as part of a broadcast target wake-up time(TWT) field using a reserved bit indicating a start of a service period(SP) that is associated with one of the BTPs.
 18. An apparatus of anaccess point (AP) station (STA), the apparatus comprising: processingcircuitry; and memory, wherein the processing circuitry is configuredto: encode a beacon frame for transmission within a beacon interval(BI), the beacon frame indicating one or more boundary time points(BTPs), wherein non-AP STAs associated with the AP STA are restrictedfrom obtaining transmission opportunity (TXOP) extending beyond any ofthe BTPs; obtain a transmission opportunity (TXOP) for a transmission toa non-AP STA; and encode a PPDU for transmission to the non-AP STAduring the TXOP.
 19. The apparatus of claim 18, wherein the TXOP is notbounded by the one or more BTPs.
 20. The apparatus of claim 18, whereinwhen TXOP acquisition by the AP STA is bounded by the one or more BTPs,the processing circuitry is further configured to either start or resumeany backoff for channel access after any one or more of the BTPs inaccordance with an enhanced distributed channel access (EDCA) channelaccess procedure.